Meganne Christian and Dr Kondo-Francois Aguey-Zinsou of the University of New South Wales have successfully used a core-shell nanostructure to store, release and reabsorb hydrogen at practical temperatures and pressures.

Aguey-Zinsou says the compound, which includes lithium and sodium, was known to be an effective storage material because it could bond large amounts of hydrogen.

"Hydrogen is a gas of very low density, so if you want to power a car with it you need big volumes," says Aguey-Zinsou. "[You would need] a five metre diameter tank to drive 400 kilometres."

"But sodium borohydride acts like a sponge, allowing you to store the same amount of hydrogen in something the size of a normal car fuel tank."

Initial hurdles

Normally the compound could only be used once because it requires temperatures above 550° Celsius to release hydrogen, causing it to break apart. It can be recombined, but only under extremely high temperatures and pressures.

"Encasing the compound in tiny nanoshells lets us fine tune their properties, making them reversible at lower pressures and temperatures, allowing them to continually reabsorb and release hydrogen," says Aguey-Zinsou.

"Initial hydrogen release is now happening at just 50°C with significant release at 350°C."

Ongoing research

Aguey-Zinsou and colleagues are currently working to better understand the features of the nanostructure, and are building a demonstration project showcasing the technology.

"It will use electricity from solar and wind energy to extract hydrogen out of water using an electrolyser," says Aguey-Zinsou. "This is then stored in a tank of sodium borohydride and used to drive a fuel cell to generate electricity at night or when there's no wind."

"The first commercial applications could be just three or four years away."